XML Pretty printer with for pretty printing text contents and aligning closing tags

Author: jurajsomorovsky

src/main/java/de/rub/nds/modifiablevariable/util/XMLPrettyPrinter.java

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+/**
+ * ModifiableVariable - A Variable Concept for Runtime Modifications
+ *
+ * Copyright 2014-2017 Ruhr University Bochum / Hackmanit GmbH
+ *
+ * Licensed under Apache License 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
+package de.rub.nds.modifiablevariable.util;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.io.StringWriter;
+import java.util.Arrays;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerConfigurationException;
+import javax.xml.transform.TransformerException;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpression;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+import org.w3c.dom.Document;
+import org.w3c.dom.NodeList;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+
+/**
+ * The goal of this class is to pretty print byte array text nodes so that text
+ * contents and closing XML tags are correctly aligned.
+ *
+ * Juraj Somorovsky <juraj.somorovsky@rub.de>
+ */
+public class XMLPrettyPrinter {
+
+    public static int IDENT_AMOUNT = 4;
+
+    public static String prettyPrintXML(String input) throws TransformerConfigurationException,
+            ParserConfigurationException, SAXException, IOException, TransformerException, XPathExpressionException {
+        Transformer transformer = TransformerFactory.newInstance().newTransformer();
+        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
+        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", Integer.toString(IDENT_AMOUNT));
+        transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
+
+        StreamResult result = new StreamResult(new StringWriter());
+        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder()
+                .parse(new InputSource(new StringReader(input)));
+
+        // XPath for selecting all text contents
+        XPathExpression xpath = XPathFactory.newInstance().newXPath().compile("//*[text()]/*");
+        // XPath for counting the number of ancestors of a current element
+        XPathExpression xpathDepth = XPathFactory.newInstance().newXPath().compile("count(ancestor-or-self::*)");
+
+        NodeList textNodes = (NodeList) xpath.evaluate(doc, XPathConstants.NODESET);
+
+        for (int i = 0; i < textNodes.getLength(); i++) {
+            String content = textNodes.item(i).getTextContent();
+            System.out.println(textNodes.item(i).getTextContent());
+            double doubleDepth = (Double) xpathDepth.evaluate(textNodes.item(i), XPathConstants.NUMBER);
+            int depth = (int) doubleDepth;
+            String emptyString = createEmptyString(depth);
+            System.out.println(depth);
+            String newContent = content.replaceAll("\n", ("\n" + emptyString));
+            // remove last white space elements from the text content to align
+            // the closing tag
+            if (newContent.length() > content.length()) {
+                newContent = newContent.substring(0, newContent.length() - IDENT_AMOUNT);
+            }
+            textNodes.item(i).setTextContent(newContent);
+        }
+
+        DOMSource source = new DOMSource(doc);
+        transformer.transform(source, result);
+        return result.getWriter().toString();
+    }
+
+    private static String createEmptyString(int depth) {
+        char[] charArray = new char[depth * IDENT_AMOUNT];
+        Arrays.fill(charArray, ' ');
+        return new String(charArray);
+    }
+
+}

src/test/java/de/rub/nds/modifiablevariable/util/XMLPrettyPrinterTest.java

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+/**
+ * ModifiableVariable - A Variable Concept for Runtime Modifications
+ *
+ * Copyright 2014-2017 Ruhr University Bochum / Hackmanit GmbH
+ *
+ * Licensed under Apache License 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
+package de.rub.nds.modifiablevariable.util;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ */
+public class XMLPrettyPrinterTest {
+
+    /**
+     * Test of prettyPrintXML method, of class XMLPrettyPrinter.
+     */
+    @Test
+    public void testPrettyPrintXML() throws Exception {
+        String input = "<modifiableByteArray>\n" + "    <originalValue>\n"
+                + "FF 01 02 03 FF 01 02 03  FF 01 02 03 FF 01 02 03\n" + "FF 01 02 03\n" + "</originalValue>\n"
+                + "</modifiableByteArray>";
+        String expected = "<modifiableByteArray>\n" + "    <originalValue>\n"
+                + "        FF 01 02 03 FF 01 02 03  FF 01 02 03 FF 01 02 03\n" + "        FF 01 02 03\n"
+                + "    </originalValue>\n" + "</modifiableByteArray>";
+        String result = XMLPrettyPrinter.prettyPrintXML(input);
+
+        assertEquals(expected.trim(), result.trim());
+    }
+
+}